The present invention relates to a small size gear pump used for equipments and systems such as a cooling system used for electronic devices, medicine feeding system used in medical field such as artificial dialysis, medicine delivery system for chemical related equipments etc., which are required to have a small and a thin package size.
Generally, in heat exchange system, water, alternative chlorofluorocarbon, alcohol kind, glycol kind, or ammonia are used as a heat medium. Pumps feeding such heat media are classified as a turbo type pump of an axial flow type or of a centrifugal type having a constant pressure and a volume type pump of a rotary type or of a reciprocating type having a constant volume. However, the conventional pumps have such draw backs as having a large size, having an insufficient suction efficiency or having high electric power consumption.
Recent electronic devises generate an extremely lot of heat in accordance with high density or high integration as seen in highly integrated circuits (IC, LSI). As a result, a system which cools with a liquid heat medium having a high heat exchange capacity is required because the conventional air cool system is not enough to cope with the demand. In the present cooling system, the pump for feeding the liquid heat medium is required to be small in size and be thin in thickness as well as to have a high efficiency and low electric power consumption, so that it may be mounted in a case of an electronic device.
As such a small size pump, one having a trochoid gear in a main body of the pump is proposed. (For example, refer to Japanese Patent Publication 2002-276658.)
In the small size pump, a motor rotates the inner gear composing the trochoid gear to shift a space generated between the inner gear and an outer gear along a rotating direction and thereby to transport a fluid in the space to a prescribed direction.
The small size pump mentioned above, however, has generally a cylindrical configuration, in which the inner gear of the trochoid gear is directly connected with the rotation shaft of the motor. In general, a cylindrical pump is apt to generate a wasted space around the place where it is installed, which provides a poor space utility.
There is therefore a room for improvement in the conventional small size pump, which drives a trochoid gear with a motor, from the view point of the space efficiency.